1. Field of the Invention
This invention relates to a passive seat belt system including means to prevent inadvertent lock up of seat belt retractors.
2. Description of the Prior Art
In certain proposed passive seat belt systems which have vehicle sensitive seat belt retractors mounted on a vehicle door, devices have been proposed to deactivate the retractor lock up mechanism whenever the door is opened. See, for example, U.S. Pat. No. 4,181,326. This has been necessary, as the accelerations generated by the door motion at the conventional retractor locations exceed the mandated lock up accelerations of the retractor. In such passive seat belt systems a lock up of the retractor during door opening would disallow further door motion as the webbing is conventionally attached to the vehicle structure adjacent the midpoint of the vehicle. Such deactivating mechanisms add undesirable cost and complexity to the system and may create certain hazards. Failure of the device to disengage when the door is closed might prevent the retractor from locking when the vehicle is exposed to crash decelerations. This type of incident would leave the occupant unrestrained and subject to injuries. It would be desirable to provide a means of allowing the vehicle doors to be freely opened without compromise to the retractor's ability to properly lock up when exposed to decelerations created by rapid stops or crash incidents (such as greater than 0.7 g in the U.S.).